1. Technical Field
This invention relates generally to journal or engine bearings for internal combustion engines, and more particularly to the construction of linings for journal bearings.
2. Related Art
Sliding-type journal or engine bearings are typically used in internal combustion engine applications for journaling a shaft of the engine. Typical engine bearings have an arcuate steel backing onto which one or more layers of relatively softer bearing metal is applied.
The steel backing provides structural rigidity to the bearing whereas the applied bearing layer or layers provide a low friction sliding surface that must exhibit a combination of seemingly incompatible properties of acceptable wear and fatigue resistance, and acceptable conformability and seizure-resistance. The first two properties call for a hard, strong bearing material, whereas conformability and seizure resistance call for a softer material of lesser strength. It is generally accepted that no one material can satisfy all criteria, since a material cannot be both hard and soft. Accordingly, the current practice is to select a material, or multiple layer materials, that compromise between the competing properties. However, the demand for ever-increasing performance of engine bearings continues to challenge ability to provide a suitable “compromise” bearing material at an acceptable cost. Modern bearings and those of the future require ever-increasing wear and fatigue resistance properties without sacrificing the conformability of the bearings. As the demands of these competing properties get driven further apart, a suitable compromise material(s) is becoming more difficult to attain.
It is an object of the present invention to overcome or greatly minimize the foregoing limitations of prior engine bearings.